You should set the RAM speed to what ever was recommended by the manufacturer. the timings should also be the right settings. Your RAM should work at lower speeds but if it can go higher you might as well (unless you want some tiny latencies for some reason).
Your RAM has been tested to run at 1600 Mhz. That however is higher than the default speed that your CPU is designed for. Rhe RAM *might* run at 1600 Mhz. without issues with your CPU and it may not. All you can do is try it. If you have stability issues, go back to the 1333 Mhz. RAM frequency and default 1.5V.
There is almost no performance advantage to running the RAM at 1600 Mhz. so if you need to run it at 1333 Mhz. all will still be fine.